Friends Against Friends: Theory of Issue Linkage and the Politics of Restraining Allies

Why do states sometimes publicly restrain their closest allies during crises, risking significant alliance discord in the process? This behavior is especially puzzling when those same states have ongoing initiatives to strengthen the alliance that require allied cooperation and approval. The puzzle deepens when this occurs during crises involving relatively weak and isolated adversaries, conditions that typically reduce fears of escalation and entrapment. Moreover, in some cases, allies generally agree that these adversaries pose a potential threat, which would normally predict alliance unity. Under these circumstances, why do some states choose to mobilize formal tools of influence to restrain allies – rather than remain neutral, opt out of armed hostilities, or merely express disagreement? This dissertation introduces two key theoretical innovations. First, existing research treats alliance discord as merely the absence of cohesion, overlooking state actions that serve as key manifestations of discord. I identify the public restraint of allies as a distinct form of state behavior worth explaining, marked by two thresholds that represent progressively more confrontational responses to allied actions during crises. Second, conventional approaches tend to analyze alliance dynamics based on crisis-specific characteristics, but I develop a theory of issue linkage arguing that state behavior toward allies during crises may be driven by entirely separate, pre-existing policy divergences within the alliance. States restrain allies when crises become linked to these separate issues through precedent-setting potential or demonstration effects. This represents a subtle form of diplomatic entanglement that may be more consequential than the highly visible military entanglements that existing alliance models tend to emphasize. I employ cross-case comparisons, process tracing, and congruence analysis to examine the 1956 Suez crisis and the 2002-2003 Iraq crisis – alongside other crises in both time periods – to explain some of the worst episodes of alliance discord in post-WWII history.